Bullseye's actually always been a really good and consistent villain! Even back in the early 80's, when grimdark material wasn't yet even a thing in non-mainstream comics, he's always been an utterly sociopathic asshole. He kills and inflicts suffering left and right, simply because he can, it amuses him and for material gain. But he's still fully rational, not some kind of Joker loon, and acts accordingly. He's an imminent threat to everything that breaths around him, but you can still understand his motivations? He's simply a evil prick that can do whatever he wants....
And he does so, all the time, even without any real super powers! He's just in prime human physical condition, with perfect knowledge of every athletic or dangerous exercise known to man, basically. You might argue that he's got superhuman powers, and I won't say you're wrong, but otoh we're talking comic books so theoretically his feats could be replicated by another person with same potential and training?
Dude's the ur-type for a dangerous sadistic asshole.